Job Overview

We are seeking a highly capable Manufacturing Engineer with a strong mechanical engineering foundation to bridge the gap between product design and scalable production.

In this role, you will partner closely with Mechanical Design Engineering to ensure our products are not only functional, but manufacturable, scalable, and robust at volume. You will play a critical role in shaping design decisions early-driving DFM/DFX, tolerance strategies, and assembly error-proofing into the product architecture.

This is not a downstream role. You will actively challenge and influence design concepts, ensuring they are suitable for high-volume production-not just prototype success.

The ideal candidate combines strong mechanical design fundamentals with hands-on manufacturing experience and thrives in collaborative, fast-paced environments.

What you'll do

Design for Manufacturability (Core Focus): Partner with Mechanical Design Engineers to translate product concepts into manufacturable, scalable solutions

• Drive DFM/DFX initiatives, including tolerance stack-ups (GD&T), datum strategy, and assembly sequencing
• Convert assembly process learnings (error-proofing, access, ergonomics) into clear design requirements
• Actively influence and challenge product design decisions using first-principles engineering and manufacturing constraints
• Contribute to design decisions with understanding of stress, interfaces, and system integration

Assembly and Equipment design: Design and develop fixtures, jigs, and assembly equipment with a focus on precision, repeatability, and cost

• Perform tolerance analysis and support detailed 2D drawing creation for fabrication
• Support early validation through prototyping, testing, and iteration
• Select and integrate actuators, sensors, and standard components; define functional sequences for automation
• Emphasize simple, robust solutions using off-the-shelf components where possible

Manufacturing Scale-Up:

• Own the transition of assembly processes from prototype builds to scalable production systems
• Plan and validate production processes using PFMEA, DOE, and capability studies (Cpk, GR&R)
• Collaborate cross-functionally with Quality, Supply Chain, and Operations to move from prototype to volume production
• Support factory layout, line design, capacity planning, and continuous improvement efforts

What you'll bring

Education and work experience:

• Bachelor's or Master's degree in Mechanical Engineering or related field
• 5+ years of experience in mechanical design, manufacturing engineering, or a hybrid role

Strong foundation in:

• Proficiency in CAD tools (e.g., SolidWorks, CATIA)
• GD&T and tolerance stack-up analysis
• 2D drawing creation for manufacturing
• Datum strategy and precision assembly
• Demonstrated experience influencing product design for manufacturability
• Experience designing assembly processes and scaling from prototype to production

Familiarity with:

• PFMEA, 8D, DOE
• Process capability (Cpk), GR&R
• Assembly technologies (fastening, machining, laser metrology)
• Willingness to travel internationally up to 15%

What Sets You Apart

• Ability to challenge design decisions with data and first-principles thinking
• Strong intuition for "what will break at scale" vs. what works in prototype
• Hands-on mindset-you're comfortable on the floor validating your ideas
• Bias for simple, cost-effective solutions over over-engineering

$116,000 - $136,000 a year

This position is onsite at our Menlo Park HQ. The salary will be adjusted to reflect local market conditions based on employee location as well as the experience of the employee. Along with the base salary, Mainspring offers pre-IPO stock options + benefits.

Does your experience not meet all of our posted requirements? Studies have shown that some people are less likely to apply to positions unless they meet every listed requirement. At Mainspring, we are committed to building a diverse, inclusive, flexible, and collaborative environment, so if you want to help us transition the world to clean and affordable electricity, and don't meet all posted requirements for a particular role, we'd still love to hear from you. Mainspring can sometimes be flexible enough to shift responsibilities for the right person, or otherwise identify open or upcoming roles that may better fit your professional background.